1. Field of the Invention
The present invention relates to plasma generators, and, in particular, to electrohydrodynamic (EHD) flow control of a discharge plasma, such as a one-atmosphere, uniform glow discharge (OAUGD) plasma.
2. Description of the Related Art
The use of magnetohydrodynamics (MHD) to control the turbulent viscous drag due to aerodynamic boundary layer flow has received considerable attention over the years. Most concepts have been based on ionized flow around a magnetized hypersonic vehicle, or on achieving such a plasma with ion seeding techniques. Emphasis has been placed on the magnetohydrodynamic approach in hydrodynamics due to the electrically conducting nature of seawater and perceived high economic or performance payoffs. However, in terms of a net energy balance, performance enhancement has proven elusive.
An alternative to MHD flow control which has received far less attention in the field of boundary layer research is based on the electric field alone, or electrohydrodynamic (EHD) control. In partially ionized gases, the electric field itself, or the paraelectric effects associated with an electric field gradient, can be used to accelerate ions and, via particle collisions (mobility drift), the neutral gas. In the past, a difficulty with the EHD approach, especially in non-hypersonic flight applications, is generating an energy-efficient ionized flow near the surface at one atmosphere.